November 2, 2013 Subject:
Balancing Chemical Equations
This is a clear, nicely-explained and helpful presentation for students. There is only one error, the gas C2H4 is said to be methane and it is said so twice. The GAS formula is actually ethene or ethylene. Methane is CH4 and ethene is C2H2.
Other than that gas identification error above, this is a good video.